It is well known that polyamides such as nylon-5, nylon-6, nylon-8, and nylon-12 have been produced by ring-opening polymerization of appropriate lactams. Nylon-6, also called polycaprolactam, was originated by I. G. Farbenindustrie in 1940. In one preparation technique, the polymerization of .epsilon.-caprolactam (also known as .epsilon.-aminocaprolactam or simply caprolactam), is carried out by adding water to open the ring and then removing water again at elevated temperature, where linear polymer forms. .epsilon.-Caprolactam may also be polymerized by ionic chain mechanisms.
Nylon-6 has properties similar to nylon-66, but has a lower crystalline melting point and is somewhat softer and less stiff. The major use for the polymer is in tire cord. Polycaprolactam accounts for about 25% of U.S. consumption of nylon.
Nylon-6 has been modified to improve its properties. See, for example, R. A. Lofquist, et al., "Hydrophilic Nylon for Improved Apparel Comfort," Textile Research Journal, June 1985, pp. 325-333 which teaches that a cotton-like moisture absorption level can be achieved by incorporating a telechelic water soluble segment, such as an amine-terminated polyethylene oxide (PEOD), into the nylon backbone, or grafting onto the nylon chain a low molecular weight poly(dimethylacryl-amide) (PDMAA). The JEFFAMINE.RTM. ED-Series amines were used as the amine-terminated polyethylene oxide glycols to produce a modified nylon-6. These amines are high molecular weight (600 to 2000) alkylene glycol diamines having the formula H.sub.2 NRNH.sub.2, where the radical R is a polyoxyalkylene chain of molecular weight of from about 200 to about 4000 having terminal carbon atoms to which nitrogen atoms are bonded. Moisture absorption was found to be greatest using the amines having the highest molecular weight.
See also European Patent 0 163 902 A1 which relates to high polymeriza-tion degree polyetheresteramides having no gelated materials and superior color tones. These polyamides are apparently quickly obtained through the polycondensing interaction carried out between (a) one or more than two polyamide forming components selected from lactams and aminocarboxylic acids as well as the salts of substantially equal quantities of diamines and dicarboxylic acid, and (b) the polyetherester forming components consisting of substantially equal quantities of dicarboxylic acids and poly(alkylene oxide) glycols, in the presence of 0.001 to 0.5 percent by weight of the mixtures composed of antimony oxides/organic tin compounds, and more preferably, in the co-presence of 0.0005 to 0.5 percent by weight of phosphoric compounds.
U.S. Pat. No. 3,454,534 indicates that the hydrophilic characteristics of nylon 66 may be improved by adding a polyakylene glycol diamine to the molten polymer prior to spinning. The process involves producing polyhexamethylene adipamide where equimolar proportions of adipic acid and hexamethylene diamine are reacted together to form molten polyhexamethylene adipamide. The improvement involved introducing from about 0.3 to 3.0 weight percent of a polyalkylene glycol diamine into the molten polymer subsequent to polymer formation and prior to spinning. The polyalkylene glycol diamine has the formula: H.sub.2 N--(CH.sub.2).sub.3 --O--[R--O].sub.x --(CH.sub.2).sub.3 --NH.sub.2 where R is an alkylene hydrocarbon radical having a chain length of from 2 to about 8 carbon atoms, and x is an integer sufficiently large to confer a molecular weight of at least 1000. Note that propylene linkages are required and that the polyalkylene glycol diamine must have a molecular weight of at least 1000.
A new class of linear nitrogen-containing copolymers and especially elastic products are described in U.S. Pat. No. 3,044,987. The substantially linear segmented copolymer consists of a multiplicity of intralinear segments of two classes connected by ester linkages, where the segments of the first class are the residues remaining after removal of the terminal ester-forming functional groups selected from the group consisting of hydroxyl, thiol, carboxyl, and acid halide from a difunctional polymer. The segments of the second class contain at least one repeating unit of a fiber-forming polymer, including a radical containing terminal nitrogens. The diamines suggested in this patent do not contain ether linkages.
Block copolymers of poly(oxa-amide) and polyamide are described in U.S. Pat. Nos. 4,113,794; 4,130,602 and 4,136,133. The '794 patent discusses novel copolymers formed by melt blending a melt spinnable polyamide, such as nylon-6, and a block of random poly(dioxa-amide), such as a copolymer prepared from the mixture of caprolactam and the salt of adipic acid and 4,7-dioxadecamethylene diamine. Block copolymers formed by melt blending a melt spinnable polyamide such as nylon-6 and a poly(dioxa-amide) such as poly(4,7-dioxadecamethylene adipamide) is disclosed in the '602 patent. The '133 patent teaches block copolymers formed by melt blending a melt spinnable polyamide such as nylon-6 and a poly(oxa-amide) such as poly(4-oxaheptamethylene adipamide). As examples only, in the '133 patent, the poly(oxa-amide) groups have the formula: ##STR1## where R.sub.1, R.sub.2 and R.sub.3 are hydrogen, C.sub.1 -C.sub.10 alkyls and C.sub.3 -C.sub.10 isoalkyls; R.sub.4 is selected from the group consisting of C.sub.0 -C.sub.10 alkylenes and C.sub.3 -C.sub.10 isoalkylenes, where y may range from 4 to 200. All of these materials are noted to have utility as fibers.
U.S. Pat. Nos. 4,044,071 and 4,045,511 describe methods for making the copolymers discussed in the previous paragraph. The '071 patent teaches a process for forming block copolymers by mixing a dry salt of a prepolyamide and a molten melt-spinnable polyamide. The mixture is heated to a temperature in the range of between the melting point of the higher melting component of the mixture to below the amide-interchange temperature of a blend of the melt-spinnable polyamide and the homopolymer which would result from the polymerization of the salt. Mixing and heating is continued until substantially all of the salt and the polyamide are converted into a block copolymer. The '511 patent teaches a similar process, but one that is lower in energy and uses a blend of dry particles of a melt-spinnable polyamide, rather than using the polyamide in the molten state.
Finally, U.S. Pat. No. 4,297,454 teaches a method for preparing a block copolymer of an ether-free polylactam and a polyetheramide, e.g., poly(4,7-dioxadecamethylene adipamide) involving polymerizing a lactam, e.g., caprolactam, in contact with the polyetheramide. At least one of the lactam and the polyetheramide are molten during the lactam polymerization and block copolymer formation. The materials prepared appear similar to those described in U.S. Pat. Nos. '794; '602 and '133, described above. Examples of polyetheramides mentioned in the '454 patent include poly(4,7-dioxadecamethylene adipamide), poly(4,7-dioxadecamethylene sebacamide), poly(4,9-dioxadodecamethylene adipamide), poly(4,8-dioxa-6,6-dimethylundecamethylene adipamide), poly(4,7-dioxa-2,9-dimethyldodecamethylene adipamide), poly(4,7-dioxadecamethylene-2-methylene adipamide), poly(4-oxaheptamethylene adipamide), and poly(4-oxa-2,6-dimethylmonomethylene adipamide).
Although nylon-6 has been incrementally improved as shown by the publications discussed above as examples, there remains a need for new polyamides having improved water absorbancy, but which retain the beneficial properties of the original polyamide materials, in this case, nylon-6.
Triethylene and tetraethylene glycol diamines may be continuously produced from glycols catalytically. The triethylene glycol diamine and tetraethylene glycol diamine products are known under the trade names JEFFAMINE.RTM. EDR-148 Amine and JEFFAMINE.RTM. EDR-192 Amine, respectively, as made by Texaco Chemical Co. These materials are useful as epoxy curing agents.